Renewable fuse plug



June 20, 1944. H. F. JOHNS 2,351,816

RENEWABLE FUSE PLUG Filed March 5 1942 1N VENTOR BY :2 E

Patented June 20, 1944 RENEWABLE FUSE! PLUG Harry JohnaKansas City, Mo., assignor to Velma V. Johns Application'March 5, 1942, Serial'Noz4335425 a claims. ((11.200-130) This" areas to electrical fuse plugs of the replaceable type} and: especially those usually employed for safeguarding circuits having a fuse block provided with a number of sockets.

The primary object of thisinvention-is to pro. vide a fuse plug ass em'bly capable of having the parts thereof separated only when the same is removed from the operative position, which-separation is forthe purpose of r enewingthe fusib1e link thereof. g v j k A yet further aim of the instant invention is to provide: a renewable fuse plug havingas the important f comppnent parts thereof a socket'ed body, an insert frictionally carried by the body; and a"pliable, v l between the bodyand plug-when thefu'se plug assembly is in theoperative position whereit is supported by a fuse block.

This invention has for a further object, the provision of a fuse plug provided with separable bodies, the zone of juncture between which is contoured to prevent accidental displacement whereby a renewable, fusible link is secured in position to complete the circuit through the fuse block.

Other objects of the invention will appear during the course of the following specification, referring to the accompanying drawing wherein:

Fig. 1 is a plan View of one end of a renewable fuse plug made in accordance with the present invention.

Fig. 2 is a longitudinal central sectional View through the plug taken on line IIII of Fig. l and showing the same in position on a fuse block.

Fig. 3 is a stretch-out view illustrating the manner in which the main parts of the plug may be separated.

Fig. 4 is a cross sectional View taken on line IV--IV of Fig. 2.

Fig. 5 is a inverted plan view of the removable insert showing a complete link in place.

Fig. 6 is an end elevational view of the fuse body.

Fig. 7 is a plan view of a link of the character employed in the fuse assembly; and

Fig. 8 is a central sectional view through an insert made in accordance with the modified form of the invention.

For purpose of illustration and making full explanation of the invention, the fuse plug as sembly has been shown in use with a conventional fuse block I0 having a contact point 12 disposed at the bottom of the cavity 14, the annular sides of which are lined with a screwfusible 'link maintained in place threaded skirtlfi of conducting material. When therenewable fuse plugc ontemplated by the present invention-is idpbsitionas' seen in Fig. 2, the component parts thereof are held irf a'ssembled relation.

The fuseplug assembly comprises'a body l8 formed of non-conducting substance, such "as glass. Glass is preferred because the hereinafter described link 20 isviewable therethrough and when said link has been melted as a result of electrical overload, the same may be seen without removing any part of the plug.

' A jacket 22 of conducting material is formed. to present externalscrewthreads by means of which-body 18 may be positioned withincavity l4. Body l8 has anaXial-sock'et 24 formed therein which extends inwardly from one end of the body. The annular side walls of body I8 are provided with notches 26 that cooperate with parts of the hereinafter described insert to preclude relative displacement.

A contact finger 28 joined to jacket 22 extends downwardly and inwardly of socket 24 and has the free end in spaced relation with the lowermost wall of one of notches 26. This finger 28 is resilient in character and moves into frictional engagement with the part which enters notch 26.

Insert 30 is formed of insulating material; has a central contact 32 on one end; and is molded to present ribs 34 engageable within notches 25 of body I8. The interengagement of notches and ribs 26 and 34 respectively, is distinctly illustrated in Fig. 4. Tongue 36 is angled upwardly and outwardly from a point on one of ribs 34. This tongue 36 is the end portion of a conductor extending into engagement with contact 32.

A groove 38 across one end of insert 30 receives link 20, which is turned laterally at both ends to maintain the same in place. The marginal end of link 20 overlying tongue 36 moves into one of notches 26 where the effective frictional relation between the two is insured. The other end of link 20 lies against the annular outer surface of insert 30 and is pressed against contact finger 28 when the insert is pressed into socket 24.

In the modified form of the invention, illustrated in Fig. 8, insert I00 has contact I02 joined by tongue I04, but this tongue extends downwardly and outwardly to be overlapped by one laterally extended end of link 20. This slight modification is illustrated and described merely to indicate that rearrangement of parts may be easily made.

When the fuse plug assembly is in the operative position, insert 30 lies between body I! and fuse block ID. A violent rupturing of link 20 will not therefore blast any part of the fuse plug assembly from the fuse block, as is now the case with a number of plug arrangements.

The circuit is completed through contact points I! and 32, tongue 30, link 20, finger 28 and jacket 22 in the customary manner. The hole 40 in the central part of link 20 may be varied in diameter to present metal capable of withstanding currents of various strengths. When body I8 is screwed into cavity l4, insert 30 will not be accidentally moved about its axis to disconnect the parts but will be held securely in place by interengaged ribs and notches 34 and 26 respectively.

The advantages arising from a fuse plug assembly of the character above described, will be obvious to those skilled in the art and while the preferred embodiment of the invention has been described in detail, it is desired to be limited only by the scope of the appended claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. A fuse plug assembly of the character described, adapted for insertion into a socketed fuse block, comprising in combination a socketed body having means for securing the plug assembly in place; a contact finger adjacent to the inner face of the body and within the socket; an insert of substantiall circular cross section frictionally held within the socket of the body having a contact point on the outer end thereof for engagement with a contact of the fuse block when the plug assembly is mounted in said block; a conductor leading from the contact point of the insert to the periphery thereof; and a fusible link frictionally held between the insert and body for bridging the space between said conductor and contact finger.

2. A fuse plug assembly of the character described adapted for insertion into a socketed fuse block, comprising in combination a socketed body having means for securing the plug assembly in place; a resilient contact finger adjacent to the inner face of the body and within the socket; an insert of substantially circular cross section frictionally held within the socket of the body having a contact point on the outer end thereof for engagement with a contact of the fuse block when the plug assembly is mounted in said block; a conductor leading from the contact point of the insert to the periphery thereof and terminating in a resilient tongue; and a fusible link having one end portion seated between said tongue and the body and having its opposite end seated between said insert and the contact finger.

3. A fuse plug assembly of the character described adapted for insertion into a socketed fuse block, comprising in combination a socketed body having means for securing the plug assembly in place and having opposed notches in its socket; a resilient contact finger extending into one of said notches of the socket; aninsert of substantially circular cross section frictionally held within the socket of the body and having opposed ribs for seating in said notches; a contact point on the outer end of the insert; a conductor leading from said contact point to the periphery of the insert and terminating in a resilient tongue for engaging the other of said notches; and a fusible link having one end portion seated ber' tween said tongue and the body and having its opposite end seated between said insert and the contact finger.

HARRY F. JOHNS. 

